We imagine Zombies as beings identical to us with respect to all physical and behavioural facts but different with respect to phenomenal facts. For example, zombies might say, just like us, ‘this grapefruit is really sour’ or ‘my left knee hurts’, but, unlike us, they have no phenomenal experiences corresponding to these utterances or to the relevant physical states. The idea of zombies has been used to construct the following argument against the physicalist approach to consciousness.